Intercoat clear is basically a basecoat paint resin with no color added. It is soft, and easily damaged. It is not meant to be used as a top coat, so it is not tough enough to stand up to the weather, or to protect a paint job like a top coat clear does.

Yes, you can clearcoat over primer, but you need to talk to your paint store about the kind of primer, and kind of final clear, and how the topcoat should be used over it.